This invention relates to laser cleaning and inspecting of surfaces. In particular the system is for use on disc surfaces which are used for recording data.
In most high technology industries, for instance, semiconductor device, hard disc or flat panel display manufacturing, improved performance is linked to the ability to reduced the feature size. Thus there is the narrower line width, smaller bit cell or pixel size. As a consequence, the size of detrimental contamination, for example, particles, steadily decreases. Hence, there is an increased demand for effective cleaning technologies, tools and processes. To reduce cost these cleaning processes need to be monitored closely.
Laser cleaning has emerged as a potential new dry cleaning technology to remove particles and other contaminants from surfaces. For example the Radiance (U.S. Pat. No. 5,024,968) process utilizes a pulsed intense light source (such as an excimer laser) in the presence of an inert gas flow over the surface to remove contamination.
With the reducing feature size the time to necessary to inspect a surface for cleanliness increases and it becomes impractical to inspect every surface or even the entire surface going through a cleaning process. Usually, samples are taken and a significant portion of these surfaces are analyzed for cleanliness.
Most commonly these inspection tools are based on light scattering. A small beam of light is directed at the surface and photomultiplier tubes detect the scattered light. The smaller the wavelength the smaller particles can be detected.
There is need top provide for an enhanced technique, system and apparatus for cleaning and inspecting surfaces
According to the invention cleaning and inspecting a surface of the substrate comprises subjecting the surface to the output of a laser source for applying a cleaning energy to the surface and thereby remove contaminants on the surface. The laser source is used for inspecting the surface being cleaned and to measure the effect of the cleaning.
The integrated laser cleaning and inspection system uses the light from laser cleaning light source as the inspection light source. The system allows:
a) in situ 100% surface inspection of every workpiece during laser cleaning
b) controlling the laser cleaning process
c) sorting the substrates based on cleanliness and damage.